FLETCHER, North Carolina (AP) — Tea party activists, once unquestioned as a benefit to the Republican Party for supplying it with votes and energy, are now criticizing party leaders at seemingly every turn.

They are demanding that Congress use upcoming budget votes to deny money for putting in place President Barack Obama’s 2010 health care reform law, despite warnings the strategy could lead to a government shutdown.

They are upset that Republicans didn’t block a Senate-passed immigration bill.

Many are outspoken opponents of any U.S. involvement in Syria’s civil war.

A recent Pew Research Center survey found that more than 7 in 10 self-identified “tea party Republicans” disapprove of the job performance of Republican congressional leaders.

Many tea party activists — who have some libertarian tendencies —advocate limited government, balancing the federal budget by sharply reducing spending without increasing taxes, and an anti-interventionist foreign policy.

Many of the major tea party groups are backing 2014 primary challengers against Republicans the activists deem too moderate, including Senate Minority Leader Mitch McConnell. The Kentucky conservative once declared it his job to make Obama a one-term president.

That leaves some Republicans quietly worried that an intraparty tussle could yield a repeat of 2012. That year, conservative candidates lost winnable Senate races, and Republican presidential nominee Mitt Romney struggled to win over conservatives while still appealing to moderate swing voters.

The health care debate puts the Republican Party in its tightest spot. Wary Republicans recall the 1995-96 government shutdowns under President Bill Clinton, who persuaded many voters to blame Republicans and House Speaker Newt Gingrich, a Georgia Republican, for that budget impasse.

McConnell, House Speaker John Boehner and other Republican congressional leaders endorse the idea to “defund Obamacare.” But some also have tried to persuade core supporters that it won’t happen because Democrats run the Senate and Obama won’t gut the health care reform law, his signature domestic achievement.

If Congress doesn’t agree on appropriations at all, then many core government functions, including some military operations and the processing of Medicare claims and Social Security applications, would stop.

But that doesn’t satisfy the tea party faithful, who say too many Republicans have welcomed their support in elections only to ignore their concerns in office.

Amy Kremer, the leader of the California-based Tea Party Express, spent much of the congressional summer break on a national tour intended to pressure Republicans into backing the defunding movement.

“My message to Speaker Boehner and (House Majority Leader) Eric Cantor and Senator McConnell is simple: If you’re not willing to fight for this, what are you willing to fight for?” she said at a recent stop in western North Carolina.

Her group has helped elected conservative favorites such as Sens. Rand Paul of Kentucky, Marco Rubio of Florida and Ted Cruz of Texas, who have driven the campaign for cutting off money for Obama’s law.

After a similar event in Atlanta, Brent Bozell of the Virginia-based ForAmerica, said: “I’d like them to stop thinking about their own re-elections for five minutes. Someone should remind House Republicans that they have the majority for a reason. They should use it.”

Cantor this past week floated the idea of passing a temporary spending bill tied to a provision that would derail the health care law. But, in an unusual twist, the plan would allow Senate Democrats to separate the “end Obamacare” provision and forward the appropriations to the president. Conservatives quickly dismissed that strategy.

Americans for Limited Government President Nathan Mehrens called it a “gimmick” and “one of the most cynical political shell games seen … in years.”

The political arm of the Heritage Foundation, now run by former Republican Sen. Jim DeMint of South Carolina, has devoted more than $500,000 to an ad campaign against several Republican members who’ve resisted the push.

Another conservative group, FreedomWorks, has sponsored dozens of town hall meetings featuring cardboard cutouts of House members and senators who declined invitations to attend the “Defund Obamacare” sessions.

Several groups joined forces for a defunding rally at Boehner’s Ohio district headquarters. The conservative anti-tax group Club for Growth has already endorsed a handful of primary challengers, including against Boehner allies.

A political action committee called the Senate Conservatives Fund spent $340,000 on a television ad criticizing McConnell that’s set to run in Kentucky until Tuesday.

“Mitch McConnell is the key to stopping Obamacare,” an off-camera announcer states. “Republicans in the Senate have the power to defeat funding for Obamacare, but they won’t use it if their leader tells them to surrender.” McConnell, the announcer continues, “wants Kentucky voters to re-elect him because he’s the Republican leader, but what good is that title if he won’t use it to help Kentucky families?”

McConnell spokesman Don Stewart said the senator stands by his position. “He’s been very vocal back home over the need to repeal, dismantle, defund the law — you name it, he’s for it,” Stewart said.

While Stewart can tick off the number of speeches McConnell gave before the law’s passage and the number of Kentucky town halls he’s held to criticize the law, it, he also acknowledges political realities facing the movement to stop Obama’s health care overhaul. “The question,” he said, “is how to do it.”

In Atlanta, Bozell said that argument amounts to “trying to have it both ways.”

“They’ll vote to repeal it,” he said. “But they won’t stand up and do everything they can to stop it.”